Alzheimer's Disease is by far the most common cause of primary dementia. Either by itself, or in combination with multiple infarcts, it accounts for almost 80% of all cases. No treatment has been established which will prevent the onset or delay the progression of Alzheimer's Disease. It is possible that known drugs would have an as yet unrecognized efficacy in this respect.
4,4'-diaminodiphenylsulfone dapsone and its didextrose sulfonate derivative Promin.TM. were first shown to have a favourable effect in treating rat leprosy in 1941 (Cowdry and Ruangsiri, Arch. Pathol. 32:632, 1941). Successful clinical trials for the treatment of human leprosy followed and these two compounds are now the most important anti-leprosy drugs. The two drugs have since been used for treating a variety of skin diseases such as dermatitis herpetiformis and efficacy has been reported in several disorders of presumed autoimmune origin such as rheumatoid arthritis, lupus erythematosus and Behcet's disease. Dapsone is a drug that has been used worldwide for over 40 years. It has been found to have few side effects and these are well understood due to extensive experience with patients taking the drug continuously for many years. To the applicants' knowledge, 4,4'-diaminodiphenylsulfone and its didextrose sulfonate derivative, and closely related antilepromatous sulfones have never been used or considered for the treatment of dementia.
Leprosy is no longer a fatal disorder, due in substantial measure to treatment with dapsone. It has anti-inflammatory action, which may seem paradoxical for treatment of an infectious disease. However. M. leprae survives in macrophages, and one of the deleterious consequences of the infection, which is reduced by dapsone, is widespread amyloidosis. Dapsone has also been reported to be effective for the treatment of various presumed autoimmune diseases, including dermatitis herpetiformis, rheumatoid arthritis, temporal arteritis, polymyalgia rheumatica, cutaneous lupus erythematosus, Behcet's disease and polyarteritis nodosa. The alternative antileprosy drugs, clofazimine and rifampicin, have also been reported to have efficacy in anti-inflammatory therapeutic applications.